It's my first model in Fusion360, I also attached step-file, so you can adjust it, to your needs.
I used PLA, but you can use any material.
Maximum printable size for Prusa MK3 is for 14pcs, I pre-prepared models for this sizes: 14pcs, 12pcs, 10pcs, 9pcs, 8pcs, 5pcs
As belt, I used this Yoga strap: https://www.alza.cz/sport/sharp-shape-yoga-strap-white-d6289981.htm
The author marked this model as their own original creation.